Apparatus for altering swing weight of a golf club

ABSTRACT

The method of adjusting the swing-weight of a golf club by moving a weighted insert within a hollow shaft of the club, preferably in the butt end portion of the shaft, to different longitudinal positions and holding the insert releasably in each selected position. One embodiment uses a split sleeve as the insert, and expands and contracts the sleeve by a screw-operated expansion and contraction mechanism including a tool inserted through the open butt end of the shaft, the tool being releasably coupled to the sleeve to move it along the shaft in the contracted condition. A second embodiment uses a lead screw on which the insert is threaded to adjust the position of the insert along the screw, which is mounted in fixed bearings in the shaft, turned by a removable hand crank from the open butt end of the shaft, and held against inadvertent movement by friction applied by the bearings.

CLAIM OF PRIORITY

This application claims priority of copending U.S. provisional application Ser. No. 60/495,612 filed on Aug. 14, 2003.

BACKGROUND OF THE INVENTION

This invention relates to golf clubs, and more particularly to the provision of means in or on a golf club for altering the “swing-weight,” or balance, of the club. The invention has particular reference to the selective alteration of the swing-weight of a golf putter.

In the golf industry, the term “swing-weight” refers to the relative distribution of the weight in a club, from the various components of the club (head, shaft, grip, tape, etc) which produce movements around a fulcrum that is established at twelve or fourteen inches from the butt end of the shaft. The preferred standard uses a fourteen-inch fulcrum. A conversion table is provided in the golf industry for indicating numerical swing-weights with alpha numeric code designations using the letters “A” to “G” and the numbers “0” and “9”, producing recognizable designations such as “C9” or “D0”. Reference is made to the websites www.bs-sports.com. Basics of golf club, and www.gcfs.com for additional details.

It is well known that variations in swing-weight produce variations in the “feel” of the club, and “feel” is a very important factor in club selection and performance and in the design and construction of custom-made clubs. Further, club manufacturers are able to introduce variations in swing-weights into their clubs by varying components in the manufacturing process, so that purchasers will have a selection to suit their taste and needs. Some manufacturers have provided head inserts of different specific gravities for varying the weights of club heads and thereby modifying the swing-weights of the clubs to suit individual users. For example, see www.serigraph.com website regarding inserts for clubs sold under the PING trademark.

The commonly used approaches for swing-weight adjustments are:

-   -   Reduce the assembled club length to lower the swing weight.     -   Increase the assembled club length to increase the swing weight.     -   Add weight to the grip end of the club to decrease the         swing-weight.     -   Add weight to the club head or tip end of the shaft to increase         the swing weight.         Club manufacturers and custom club builders typically use these         methods.

SUMMARY OF THE INVENTION

The present invention resides in a novel method, and apparatus for practicing the method, of altering the swing-weight of a golf club selectively preparatory to making a particular shot, or for use under a particular set of conditions leading the golfer to desire a change in swing-weight. The invention is particularly well suited for use in putters, to satisfy the needs of golfers who wish to change the swing-weight for various reasons, including variable environmental conditions affecting the “speed” of greens.

For thee purposes, the invention provides a movable weighted insert in the shaft of the club, preferably in the butt end portion thereof, and a mechanism for selectively adjusting the position of the weighted insert along the shaft and locking the insert in different selected positions. For compliance with the rules of golf, the mechanism can be made to be usable only in a manner that is visible to other players, so that those players will know about any adjustment. A separable adjustment tool preferably is provided, to be removable after adjustments are made, or the tool may be built into the club.

The apparatus for practicing the method may take various forms, basically comprising the weighted insert disposed in the hollow shaft of the golf club, and a means for positioning the insert in different selected positions within the shaft and holding it in the selected position during use of the club. The presently preferred apparatus comprises an expandable and contractible insert that is movable longitudinally of the shaft in the contracted condition, a connector for moving the insert in contracted condition to different longitudinal positions in the shaft, and a mechanism for selectively expanding and contracting the insert to fix the insert in a selected longitudinal position and to release the insert for movement to a different position. The preferred mechanism for these purposes is a screw mechanism actuated by a manually operable tool that is releasably connectable to the insert and serves as the connector for moving the insert to different selected positions. The tool is removed prior to play.

A second embodiment of the invention comprises an insert in the form of an internally threaded weight that is adjustably positioned within the hollow shaft on an elongated lead screw that extends through a selected range of possible adjustment for the insert and is designed to remain in place in the shaft, with one end of the screw accessible at the end of the shaft. The insert is non-rotatably mounted in the shaft, and the lead screw is rotatably supported in fixed bearings so as to move the weight along the screw in different longitudinal directions during turning of the screw in different directions. Inadvertent turning of the screw is prevented by frictional resistance in the bearings. A hand actuator is provided at the accessible end of the lead screw, preferably a hand crank that can be coupled releasably to the lead screw at an open end of the shaft. A rotating cap on the end of the shaft can serve the same function.

Other aspects and advantages of this invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a representative golf club equipped with the present invention, with internal parts shown in broken lines;

FIG. 2 is an enlarged fragmentary cross-sectional view taken longitudinally through the butt end portion of the representative club in FIG. 1, with the addition of an optional end cap for the club;

FIG. 3 is a further enlarged, exploded cross-sectional view of the weighted insert and mechanism for expanding and contracting the insert;

FIG. 4 is an end view of the expansion nut, taken along line 4-4 of FIG. 3;

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 3;

FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 2;

FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. 3, with the parts in assembled positions;

FIG. 8 is an enlarged cross-sectional view taken along line 8-8 of FIG. 2;

FIG. 9 is a greatly enlarged isolated side elevational view of the apparatus of the invention in the golf club in FIG. 1, with a portion of the tool removed, and with a modified embodiment of the mechanism for expanding the insert;

FIG. 10 is an exploded side elevational view of the modified embodiment of FIG. 9, without the tool;

FIG. 11 is a side elevational view of the modified embodiment in assembled condition;

FIG. 12 is a side elevational view of a prior art apparatus for measuring “swing-weight”, with a “wood” golf club shown during a measuring operation;

FIG. 13 is a representation of a prior art conversion table of swing-weight designations;

FIG. 14 is an enlarged longitudinal cross-sectional view similar to FIG. 2 but showing a portion of a club equipped with an alternative embodiment; and

FIG. 15 is an enlarged side elevational view of the weighted insert in the alternative embodiment.

DETAILED DESCRIPTION OF THE FIRST EMBODIMENT (FIGS. 1-8)

Shown in FIGS. 1 through 11 for purposes of illustration is the first embodiment of the apparatus of the invention, for altering the swing-weight of a golf club such as the representative club 11. This club is basically conventional in construction, comprising an elongated hollow tubular shaft 12 that is generally cylindrical but often tapers slightly from a butt or grip end 13 to a tip end portion 14, a club head 15 mounted on the tip end portion, and a grip 16 applied to the butt end portion in a conventional manner. The shaft 12 the club 11 may be composed of various materials, usually composites or metal. The illustrative club 11 has a putter head 15, this being the typical application for the present invention.

As has been noted as background, an important characteristic of golf clubs is referred to as “swing-weight”, which refers to the relative distribution of the weight in a club, or its center of gravity along its length. FIG. 12 shows a conventional apparatus 17 for measuring swing-weight about a fulcrum at 18, which may be fourteen inches from the butt end 19 of the club 20 shown in FIG. 12, through a scale 21 that holds down the butt end while the tip end portion of the club 20 and the head 22 are supported cantilever fashion beyond the fulcrum 18. Shown in FIG. 13 is a portion of a conventional conversion table 23 that indicates the alphanumeric code designations that produce recognizable swing-weight designations, such as “C9” or “D0”. The present invention provides a golf club whose swing-weight is selectively adjustable along the scale to different selected values for different conditions.

In accordance with the present invention, the apparatus 10 comprises generally a weighted insert, indicated generally at 25, disposed in the hollow shaft 12, and means for positioning the insert in different selected positions within the shaft, herein in the butt end portion thereof, to vary the swing-weight of the shaft selectively. This enables the golfer to make fine adjustments that the golfer deems desirable for particular golfing conditions, and is intended primarily for use in varying the swing-weight of putters for different conditions of the greens, and can be accomplished with a relatively simple, lightweight mechanism that does not adversely affect the performance of the club.

More specifically, in the illustrative first embodiment of the apparatus 10, the insert 25 is a generally cylindrical elongated weight with an outside diameter slightly less than the inside diameter of the shaft, and may have a slight taper matching the taper of the inside surface 27 of the shaft, when the shaft is tapered. This insert is adjustably positioned within the shaft by means of an expansion and contraction mechanism within the insert, indicated generally at 28 in FIG. 3, and a connector, indicated generally at 29, for moving the insert in contracted condition to different selected positions and then expanding the insert into tight engagement with the shaft. The connector 29, as shown in FIGS. 1 and 2, is an elongated tool that can reach the insert through the end 13 of the shaft and actuate the expansion and contraction mechanism 28 to loosen the insert 25 and move it to a different position.

As can be seen most clearly in FIGS. 2 and 3, the insert 25 is a sleeve that is split longitudinally into two separable halves 30 that define a central bore 31 in the insert and two outwardly flared end surfaces 32 and 33 at the ends of the bore. These surfaces form cams in the insert for engaging complementary cam surfaces 34 and 35 of the expanding and contracting mechanism 28. The cam surface 34 is on the end of an expansion nut 37 that is fitted into the flared end 32 of the bore 31 and is internally threaded onto the free end portion of a screw 38 that extends through the bore 31. The cam surface 35 is formed on the end 33 of the head 39 on the opposite end of the screw and is disposed within the flared end 33 of the bore 31 in the insert. The assembled condition is shown in FIG. 2.

The connector tool 29 is a manual actuator for the expansion and contraction mechanism 28 and comprises an elongated stem in the form of a rod 40 that is smaller than the interior of the butt portion of the shaft 12. This rod is long enough to reach into the shaft from the butt end 13 and become engaged at its inner end with the expansion and contraction mechanism 28, wherever it is within the range of adjustment designed for the insert 25. A handle 41 is mounted on the outer end of the rod 40 to facilitate gripping and turning of the rod, and the inner end has a releasable connection 42 for engaging the expansion and contraction mechanism. Herein, this releasable connection is a simple square socket 43 in the end of the head 39, the right end in FIGS. 2 and 9, and a complementary square socket driver 44 on the end of the rod 40 for turning the head as the rod is turned by the handle 41. This draws the expansion nut 37 toward the head 39 in one direction of rotation, causing the interacting cam surfaces 32, 34 and 33, 35 to expand the insert into tight engagement with the shaft. In the opposite direction of rotation, the screw 38 drives the nut 37 away from the head 39 and permits the sleeve to contract or collapse. A spline coupling between the shaft and the expansion and contraction mechanism prevents rotation of the latter in the shaft, this coupling being formed by a longitudinal rib 45 (FIG. 2) on the inside surface of the shaft 12.

Two peripheral grooves 48 preferably are formed in the insert, around both sleeve halves 30, as shown in FIGS. 2 and 3, and two resiliently flexible rings 49 (FIG. 2) are mounted in these grooves to hold the sleeve halves against the expansion and contraction mechanism and contract the insert when permitted by the mechanism. Thus, the insert responds positively to both expanding and contracting rotation of the connector tool 29. The rings may be split wire rings with overlapped ends permitting expansion of the rings.

The connector tool 29 has a releasable longitudinal coupling for engagement with the insert 25 to move the latter along the shaft to selected longitudinal positions while in the contracted condition. A simple and convenient coupling for this purpose is a spring-loaded ball detent 50 on one side of the socket driver 44, as shown in FIG. 9, that is releasably engageable with a detent recess 51 in one sidewall of the socket 43 when the driver is inserted in the socket, each wall preferably having such a recess. The detent ball 50 snaps into a detent recess and is held yieldably in place by the spring 51 behind the ball, with sufficient force to permit the tool to pull the insert along the interior of the shaft to a new selected position close to the butt end 13. Alternatively, a shoulder 52 on the rod 40, at the driver 44, engages the opposed end 53 of the adjusting screw to push the insert farther into the shaft. Then, after the insert is expanded and set in the selected new position, the tool is uncoupled simply by pulling on the handle with sufficient force to overcome the holding force of the ball detent.

DETAILED DESCRIPTION OF THE MODIFIED EMBODIMENT (FIGS. 9-11)

A modified embodiment of the apparatus 10 is shown in FIGS. 9-11, and provides a specifically different insert and expansion and contraction mechanism. This is intended for use with a tool like the tool 29 of the first embodiment, which is not described again at this time. The modified embodiment uses a weighted insert 60 similar to the insert 25 of the first embodiment and having an actuating screw 61 that carries a head 62, similar to the head 39 of the first embodiment. The head has a non-circular socket 63, for receiving the socket driver 44 of the placement tool 29, and detent recesses 64 are formed in the inner walls of the socket for engagement with the ball detent. The screw 61 extends loosely through a first expansion nut 65 and a central coiled spring 67 and is threaded into a second expansion nut 68 on the opposite side of the spring, the two expansion nuts being positioned at the opposite ends of a split sleeve similar to the sleeve 25. This sleeve comprises two separate halves 70 and 71 that are fitted together around the adjacent end portions of the two expansion nuts and held together by a resiliently extendable ring 72 fitted in a groove 73 extending around the two halves. This ring may be a metal C-ring.

Each of the expansion nuts 65 and 68 has wedge-shaped cam wings 74 on its opposite sides, and each cam wing has upper and lower inclined cam surfaces 75 and 77 that are engageable with opposed inclined cam surfaces 78 and 79 on the split sleeve. These surfaces are designed to expand the split sleeve evenly along the entire length as the expansion nuts are drawn into the sleeve ends by the screw 61 and the cam wings 74 are simultaneously drawn into engagement with the opposed cam surfaces 78 and 79. This also compresses and loads the spring 67 between the expansion nuts.

As the screw 61 is turned in the opposite direction to spread the expansion nuts, assisted by the spring 67, the cam surfaces permit the sleeve to contract, assisted by the ring 72. The result is smooth and uniform expansion and contraction of the insert. In other respects, the modified embodiment is the same as the first embodiment, and corresponding parts are indicated by the same reference numbers used in the first embodiment.

DETAILED DESCRIPTION OF THE ALTERNATIVE EMBODIMENT (FIGS. 14 and 15)

Shown in FIGS. 14 and 15 is an alternative embodiment 80 of an apparatus for altering swing-weight in accordance with the invention, in which a moveable weighted insert 81 is adjustably supported in the golf club shaft 12 on a lead screw 82 that is rotatably supported on the shaft and has an accessible end at the open end 13 of the shaft for engagement with a removable hand crank 84. The insert 81 is non-rotatably supported in the shaft, and herein is spline-coupled to the shaft wall by a rib 45 fitted in a longitudinal groove 47 in the insert, as in the first embodiment, and is threaded onto the lead screw so that turning of the lead screw 82 in one direction or the other moves the insert 81 back and forth within the shaft.

To mount the lead screw 82 on the shaft 12 in this manner, two bearings 85 and 87 are fitted tightly in the shaft at the opposite ends of the screw, and permit rotation of the screw while preventing longitudinal motion.

On the outer, or left, end of the screw at the end 13 of the shaft, is a head 88 that forms a releasable coupling for driving engagement with the hand crank 84. The crank, which may have a grip 89 at its free end, has a drive socket 90 for fitting over the head 88 as shown in FIG. 14. When thus engaged, turning of the crank turns the screw to move the insert. To resist inadvertent movement, the lead screw is fitted snugly in the bearings 85 and 87, which frictionally resist turning of the screw until a substantial turning force is applied by the hand crank 84. When the crank is removed, the end 13 of the shaft may be covered by a cap (not shown), similar to the cap shown on FIG. 2.

CONCLUSION AND SUMMARY OF THE METHOD OF THE INVENTION

It will be seen from the foregoing that the present invention provides different relatively simple and lightweight apparatus for adjustably positioning a weighted insert within the shaft of a golf club to vary the swing-weight of the club selectively and easily when desired. It also will be seen that the apparatus that have been disclosed satisfy the requirement that such adjustment be visible to other players. Apart from this requirement, the hand crank of FIG. 14 could be replaced by a permanent rotary cap coupled to the lead screw to make adjustments in swing-weight without need for a separate tool.

While the steps in the method of the invention should be evident from the foregoing descriptions of the mechanisms, the following will provide a functional summary of the steps of the method. The initial steps are: providing a weighted insert to be fitted into the elongated hollow shaft of the golf club, and providing a means in the shaft for adjustably positioning the insert within a selected portion of the shaft in different selected positions, different mechanisms have been disclosed for this purpose. The preferred location of the insert and the mechanism is the butt end portion of the shaft, within the twelve to fourteen inches of the butt that typically are disposed on one side of the fulcrum 18 when swing-weights are measured on a device of the kind shown in FIG. 12. When these preparatory steps are complete, the swing-weight is adjusted by using the adjustment mechanism to move the insert from one position to another selected position, and securing the insert in its new position. The result is a simple, easy and effective adjustment of the swing-weight.

Although different embodiments have been disclosed and described in detail herein, it will be apparent that modifications and changes may be made by those skilled in the art within the scope of the invention. 

1. The method of adjusting the swing-weight of a golf club having an elongated hollow shaft comprising the steps of: providing a weighted insert; providing means for adjustably positioning the insert within the shaft; and adjusting the position of the insert along the shaft to adjust the swing-weight of the club
 2. The method defined in claim 1 wherein the insert is positioned in the butt end portion of the shaft.
 3. The method defined in claim 1 wherein the club is a putter and the swing-weight is adjusted for varying environmental conditions.
 4. In a golf club having an elongated hollow shaft formed with a tip end and a butt end, an apparatus for selectively altering the swing-weight of the golf club, comprising: a weighted insert in said shaft comprising an elongated radically expandable and contractible sleeve, and sleeve having an outside diameter that is contractible for size smaller than the interior of the shaft so as to be moveable longitudinally therein; mechanism for selectively expanding and contracting a wedge mechanism within said sleeve including a screw actual or having a drive connector accessible from one end of the sleeve and operable to expand and contract the sleeve upon turning of the drive connector in opposite directions; and a connector tool having a stem for extending into the shaft from one end of the shaft, and a driver on said stem releasably engageable with said drive connector and operable, upon turning of the tool in opposite directions, to turn the drive connector in opposite directions to expand and contract said sleeve; and a releasable detent acting between said tool and said sleeve to move the O sleeve longitudinally ion the shaft when the tool is engaged with the drive connector and is moved longitudinally of the shaft, thereby to position the sleeve in the shaft in the contracted position of the sleeve and to hold the sleeve in the selected position while the connector tool is turned to expand the sleeve into tight engagement with the shaft.
 5. Apparatus as defined in claim 4 wherein said insert is positioned in the butt end portion of the shaft and the shaft has an open butt end for insertion of said connector tool.
 6. Apparatus as defined in claim 4 wherein said connector tool has an elongated item insertable in the shaft through said open end, a handle on the outer end for turning of the tool, and a drive socket on the inner end forming said driver.
 7. Apparatus as defined in claim 4 wherein said sleeve comprises longitudinally split sections defining a hole having outwardly flared end surfaces forming cams of said mechanism, and said screw actuator is an elongated screw extending through said sleeve and threaded into an expansion nut at one end of the sleeve and having a head and an expansion cam at the other end of the sleeve whereby said sleeve is expanded as said nut is drawn toward said head during turning of the screw actuator.
 8. Apparatus as defined in claim 7 wherein said mechanism also includes spring means for yieldably contracting the sleeve to hold the end surfaces against the expansion nut and the screw head.
 9. Apparatus as defined in claim 8 wherein said spring comprise at least one resiliently extendable and retractable ring around said sleeve
 10. Apparatus is defined in claim 7 wherein said expansion cam at the other end of said sleeve is on a second expansion nut freely moveable relative to said screw head, and further including spring means yieldably acting between said expansion nuts to spread them apart, thereby holding the cam surfaces on the nuts against said sleeve.
 11. Apparatus as defined in claim 10 wherein said spring means is a coiled compression spring disposed around said screw between said expansion nuts.
 12. Apparatus as defined in claim 10 further including wedge-shaped cams on said expansion nuts and opposed cam surfaces on said sleeve for co-acting to expand the sleeve.
 13. Apparatus as defined in claim 4 wherein said releasable detent comprises a spring-loaded ball detent connection between said driver and said drive connector.
 14. In a golf club having an elongated hollow shaft formed with a tip end and a butt end, an apparatus for selectively altering the swing-weight of the golf club, comprising: a weighted insert in said shaft comprising an internally threaded nut having an outside diameter sized to fit movably in the shaft; and mechanism for selectively positioning the insert within the shaft comprising an elongated lead screw threaded through said insert and rotatably supported in the shaft in a longitudinally fixed position, said lead screw having one end accessible at one end of the shaft, and an actuator at said one end for turning the lead screw selectively to position the insert in different longitudinal positions within the shaft, thereby to adjust the swing-weight of the golf club.
 15. Apparatus as defined in claim 14 wherein said insert and said lead screw are disposed in the butt end portion of the shaft and the shaft has an open butt end for access to said one end of the lead screw.
 16. Apparatus as defined in claim 14 wherein said lead screw is supported in longitudinally fixed bearings in the shaft.
 17. Apparatus as defined in Claim 16 wherein said apparatus has parts sized to hold the insert snugly but movably in each selected position, thereby to avoid inadvertent movement of the insert.
 18. Apparatus as defined in claim 17 wherein said bearings tightly engage the lead screw to apply frictional resistance to turning of the lead screw.
 19. Apparatus as defined in claim 15 wherein said actuator is a hand tool that is removably engageable with said one end of said lead screw.
 20. Apparatus as defined in claim 19 wherein said actuator is a hand crank having a releasable coupling for engaging said lead screw, and is removable during play.
 21. In a golf club having an elongated hollow shaft formed with a tip end and a butt end, an apparatus for altering the swing-weight of the golf club, comprising a weighted insert disposed in said shaft; and means for moving said insert selectively along the shaft and holding the insert in different longitudinal positions, thereby to adjust the swing-weight of the shaft.
 22. Apparatus as defined in claim 21 wherein said means comprise a screw mechanism having an actuator releasably coupled to the insert and operable upon turning of the actuator to move the insert to different selected positions.
 23. Apparatus as defined in claim 22 wherein said insert is an expandable and contractible sleeve, and said screw mechanism is operaable to contract the sleeve for movement along the shaft and to expand the sleeve into tight engagement with the shaft.
 24. Apparatus as defined in claim 23 wherein sleeve is movable by said actuator to different longitudinal positions when the sleeve is contracted.
 25. Apparatus as defined in claim 22 wherein said actuator is a lead screw that is rotatably supported in said shaft in a longitudinally fixed position, and said insert is threaded onto said lead screw for movement along the screw to different longitudinal positions.
 26. Apparatus as defined in claim 25 wherein said actuator is a hand crank releasably engageable with one end of said lead screw.
 27. Apparatus as defined in claim 25 wherein said insert is held frictionally in each selected position in said shaft.
 28. Apparatus as defined in claim 21 whereon said golf club is a putter.
 29. In a golf club having a shaft having a hollow butt end portion, apparatus for selectively adjusting the swing-weight of the club, comprising: a weighted insert disposed in said hollow butt end portion and movable therein to different longitudinal positions; means operable from outside the golf club to move the insert to a selected longitudinal position within said butt end portion of and means for holding the insert in each selected position, and permitting movement of the insert to a different portion when a different swing-weight is desired. 